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Panel Mount Lamp LED conversion 


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Panel Mount Lamp LED 


Written By: Scott W Vincent 


Alligator test/jumper cable set (1) 

For connecting power during testing - 
may use regular wire as well 

Battery. 9V(1) 

or other 9v DC power source (for 

Desoldering Bulb (1) 
Desoldering braid may also work 

Helping hands tool with magnifier (1) 

Optional - use to hold small parts while 
soldering them together 

Soldering iron (1) 
Wire cutter/stripper (1) 


LED. 5mm. red (1) 

120- Volt Neon Red Jumbo Lamp 
Assembly Radioshack Part #272-710 (1) 

1/4W470ohm resistor (1) 

You may substitute a different value 
based on source voltage 


In this guide we'll take a 120v AC panel mount lamp and convert it to use an LED, allowing it 
to be powered from DC voltage instead of AC. If you can handle some basic soldering and 
desoldering, then this should be an easy project! 

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Page 1 of 6 

Panel Mount Lamp LED conversion 

• Lamp assembly - I'm using Radio 
Shack part #272-710. It's 
inexpensive, and easy to take 
apart, both of which make it great 
for this project. 

• You don't have to use the 
Radio Shack lamp. You 
may find another assembly that 
works just as well - maybe in 
another color. 

• Resistor - I'm planning to use my 
lamp in a 9v DC circuit, so I've 
selected a 470 ohm resistor. 
Assuming a forward voltage of 2v 
for the LED, this results in 15ma of 
current through the LED at 9v. 

• If you want to use a 
different source voltage, 
you'll need a different resistor. I 
suggest checking out 
http://led.linear1 .org/led.wiz for 
help in calculating the needed 
resistor if you're unsure. 

• LED - a pretty basic 5mm red LED. 

• If using a different lamp 
assembly, select an LED 
that matches the color of the 
assembly's lens. 

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Panel Mount Lamp LED conversion 





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• To disassemble the lamp 
assembly, hold the top firmly while 
twisting the base clockwise. This 
unlocks it from the top and you 
should be able to pull it away now. 

• The base will have a resistor and 
bulb attached to the two solder 
terminals. Remove both by 
desoldering them from the 
terminals. There is quite a bit of 
solder, so a desoldering bulb or 
pump may work best, but braid 
may work as well. 

The removed bulb and 
resistor will not be used, 
and can be saved for other 
projects or discarded. 

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Page 3 of 6 

Panel Mount Lamp LED conversion 


# Trim the leads on one side of the 
LED and resistor and solder them 

• It doesn't matter which 
sides you trim - but make 
sure to take note of which side 
of the LED is the anode and 
which side is the cathode. The 
longer lead is the anode, but this 
may not be true after trimming! 

• Insert the soldered LED and 
resistor into the holes on the base 
where the previous bulb and 
resistor were installed. Try to keep 
the height of the LED about the 
same as the height of the previous 

• If you have trouble 
inserting the new parts, 
there may be some solder on the 
terminal(s) getting in the way, or 
you may need to bend the 
terminals to ensure that the 
leads can get through. 

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Page 4 of 6 

Panel Mount Lamp LED conversion 

• Insert the base into the lamp assembly, ensuring that the LED doesn't get stuck and has 
clearance to fit inside. Make a mental note of which side is positive (anode) and which side 
is negative (cathode). 

• With the base firmly in place, twist it counter-clockwise to lock it to the rest of the 

• Use a black marker or tape to cover the 1 10-125v voltage specification on the lamp 

• Use a silver marker to mark the housing with the proper source voltage (9v DC in the 
example) and mark the terminals positive (+) and negative (-). 

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Panel Mount Lamp LED conversion 

• Test the lamp. 

• Connect the lamp to a power source that provides the needed voltage. 
• Make sure the polarity is correct before powering it on! 

If it lights up, great! You have a working DC voltage panel lamp. 

• If it doesn't light up, check the polarity - you may have it connected backwards 
If that's not the issue, you'll have to check the soldering - is everything 
connected properly? 

This document was last generated on 201 3-01 -1 4 07:32:1 2 AM. 

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